(Python) algorithm to randomly select a key based on proportionality/weight

Question

I\'m a bit at a loss as to how to find a clean algorithm for doing the following:

Suppose I have a dict k:

>>> k = {\'A\': 68, \'B\': 62, \'         


        

Answer 1

The simplest way of doing this when your weights are relatively small integers (such as in your example) is to build a long string containing all the characters in the appropriate weights and choose a character at random from it:

import random
d = {'A': 68, 'B': 62, 'C': 47, 'D': 16, 'E': 81}
s = ''.join(k*v for k,v in d.items())
random.choice(s)

Note though that this method will use quite a lot of memory if your weights are large, in which case you might prefer a different solution.